The pathogenesis of retinal ganglion cell (RGC) dysfunction and death from glaucoma is unknown. Ischemia and mechanical distortion in the optic nerve at the level of the lamina cribrosa may be important contributing factors. The goals of this proposal are to 1) develop primary cell cultures of RGCs from neonatal rat retinae; 2) make baseline observations regarding cell viability, differentiation, and neurite outgrowth; and 3) increase survival time and enhance neurite projection by co- culturing RGCs with immature astroglial cells, appropriate portions of the central nervous system, and nerve growth factor. A successful cell culture system could readily be used to evaluate the effects of graded levels of hypoxia and focal mechanical trauma on axonal transport, electrical competence, and overall cell viability. This basic information is currently lacking, and is required to form an understanding of the pathophysiology of glaucomatous optic nerve damage. RGCs will be labelled with fluorescent dyes injected into the contralateral superior colliculus. The animals will be sacrificed 48-72 hours later and the retinae dissected, digested, dissociated by trituration, and plated on coated culture dishes. RGCs will be identified in vitro with fluorescent microscopy. Survival time and neurite projection will be enhanced by culturing dissociated RGCs on a monolayer of immature astrocytes, in the presence of portions of neonatal rat brain, and with nerve growth factor. The principal investigator is a clinician with limited research experience and belongs to the "target population" of investigators for this grant program. The program is a high risk venture which could lead to a major research endeavor of considerable importance.